Regulation and control
The U.S. FAA Laser Free Zone extends horizontally 2 NM (3,700 m) from the centerline of all runways (two dark lines in this diagram) with additional 3 NM (5,560 m) extensions at each end of a runway. Vertically, the LFZ extends to 2,000 feet (610 m) above ground level.
The U.S. FAA Critical Flight Zone extends horizontally 10 nmi (19 km) around the airport, and extends vertically to 10,000 feet (3,000 m) above ground level. The optional Sensitive Flight Zone is designated around special airspace needing bright-light protection.
In the United States, laser airspace guidelines can be found in Federal Aviation Administration Order JO 7400.2, Chapter 29 "Outdoor Laser Operations", and bright light airspace guidelines are in Chapter 30 "High Intensity Light Operations".
In the United Kingdom, CAP 736 is the "Guide for the Operation of Lasers, Searchlights and Fireworks in United Kingdom Airspace." 
For all laser users, the ANSI Z136.6 document gives guidance for the safe use of outdoor lasers. While this document is copyrighted by ANSI and is relatively costly, a flavor of its recommendations can be seen in NASA's Use Policy for Outdoor Lasers.
The U.S. FAA has established airspace zones. These protect the area around airports and other sensitive airspace from the hazards of safe-but-too-bright visible laser light exposure:
The Laser Free Zone extends immediately around and above runways, as depicted at right. Light irradiance within the zone must be less than 50 nanowatts per square centimeter (0.05 microwatts per square centimeter). This was set at "a level that would not cause any visual disruption."
The Critical Flight Zone covers 10 nautical miles (NM) around the airport; the light limit is 5 microwatts per square centimeter (μW/cm²), determined to be the level at which glare becomes significant.
The optional Sensitive Flight Zone is designated by the FAA, military or other aviation authorities where light intensity must be less than 100 μW/cm². This might be done for example around a busy flight path or where military operations are taking place. This was identified as the limiting level beyond which flash blindness and afterimages could occur.
The Normal Flight Zone covers all other airspace. The light intensity must be less than 2.5 milliwatts per square centimeter (2500 μW/cm²). This is about half of the Class 3R power level.
For non-visible lasers (infrared and ultraviolet), the irradiance at the aircraft must be eye-safe—below the Maximum Permissible Exposure level for that wavelength. For pulsed visible lasers, the irradiance at the aircraft must be both eye-safe and must be at or below any applicable FAA laser zone.
In the UK, restrictions are in place in a zone that includes a circle 3 nmi (5.6 km) in radius around an airport, plus extensions from each end of each runway. The runway zones are rectangles 20 nmi (37 km) in total length and 1,000 meters (3,300 feet) wide, centered about each runway.
This is from Wikipedia. I also checked the FAA’s site but could not find anything definitive except if you’re caught pointing any laser at a plane there are big fines and potential imprisonment. I have no working knowledge of lasers and would like to know what you think. Do the power of the lasers mentioned on the Wikipedia page come into play in astronomy?